The short answer
Normal moles usually do not change. The NHS asks you to see a GP about a mole that has changed size, shape or colour, and about any spot that itches, bleeds or crusts for more than four weeks.
The NHS says normal moles usually do not change over time, and a mole that changes size, shape or colour should be seen by a GP.
The NHS describes melanoma as often an uneven shape, a mix of two or more colours, and often more than 6mm wide, though it can be smaller.
The NHS also lists moles that are swollen and sore, bleeding, itchy or crusty as signs to get checked.
For non-melanoma skin cancer, the NHS says to see a GP about a growth or patch that hurts, itches, bleeds, crusts or scabs for more than 4 weeks.
Watch: When is a mole worth checking?
1 min 3 sec · Captioned · Normal moles usually don't change — the ABCDE signs worth checking.
Educational only — this video explains general report language and is not medical advice. Only your care team can say what a result means for you.
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The full explanation.
Change is the signal, not size
Most guidance about moles gets remembered as a size rule. That is not quite what the NHS says.
Its line is that normal moles usually do not change over time, and that a mole which changes size, shape or colour may be a melanoma. So the question to ask about a spot is not "is it big?" but "is it doing something?"
That is also why this is one symptom where waiting to see is the wrong instinct. Waiting produces more change, which is the finding you already have.
Melanoma next to a normal mole
The NHS sets the two side by side, which is more useful than a checklist.
- Shape. Normal moles are usually round with smooth edges. Melanomas are often an uneven shape, sometimes with two differently shaped halves and ragged edges.
- Colour. Normal moles are usually one colour. Melanomas often mix two or more.
- Size. Normal moles are often about the width of the end of a pencil or smaller. Melanomas tend to be bigger, often more than 6mm across, though they can be smaller when found early.
- Behaviour. Normal moles usually stay the same. A mole that changes size, shape or colour may be melanoma.
Moles that itch, bleed or crust
Beyond shape and colour, the NHS lists other signs to look for: moles that are swollen and sore, bleeding, itchy, or crusty.
A separate NHS page covers the commoner skin cancers. There the advice is to see a GP about a growth on your skin that is getting bigger or has changed colour or texture, or about a growth or area of skin that hurts, itches, bleeds, crusts or scabs for more than 4 weeks.
Four weeks is the useful number for a spot that will not settle.
Places people forget to look
Melanoma tends to appear on skin that gets a lot of sun. But the NHS notes that rarer types can affect the eyes, the soles of the feet, the palms of the hands and the genitals.
That matters because those are the places nobody checks. A new dark spot on a sole or palm, or a new dark line down a nail, is worth showing a GP for the same reason as any changing mole.
Use a mirror for your back, or ask someone to look.
Taking a photograph that helps
A GP sees your mole once. A photo lets them see it twice.
Put a ruler, a coin or a fingernail beside the spot for scale. Use daylight if you can, and hold the camera steady at about a hand's distance. Save the date. Take the next one from the same angle a few weeks later.
If you have older holiday photos that happen to show the same patch of skin, bring those too.
What happens at the appointment
The NHS says a GP may ask about your health, your symptoms and how much time you spend in the sun, and will look at the affected skin. They may ask to take a photograph to send to a dermatologist.
You may then be referred for more tests. The NHS is careful to add that a referral does not mean you have cancer. Our page on preparing for appointments covers what else is worth bringing.
When to get help sooner
- Call your GP or care team the same day if a mole or spot is bleeding and will not settle, or has become swollen, sore and weepy.
- Call your GP or care team within a day or two to book an appointment if a mole has changed its size, its shape or its colour, if it has taken on uneven edges or two or more colours, or if a growth or patch of skin has hurt, itched, bled, crusted or scabbed for more than 4 weeks. The same applies to a new dark spot on a palm or sole, and to a new dark line running down a nail.
Sources
Words to know
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Common questions
How fast should I get a changing mole looked at?
The NHS lists it as non-urgent advice, which means book a GP appointment rather than go to A&E. Book it rather than waiting for more change, since the change itself is the thing being assessed.
What does a suspicious mole actually look like?
The NHS compares them directly. Normal moles are usually round with smooth edges and one colour. Melanomas are often an uneven shape with uneven edges, mix two or more colours, and tend to be bigger.
Is it worth taking a photograph?
Yes. A dated photo next to a ruler or coin gives the GP something the examination alone cannot: a record of what the spot was doing before you came in.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Write down timing, severity, changes, and questions before you talk with a clinician.
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Sources last checked: 2026-08-09 what this meansLast updated: 2026-08-11Next planned review: 2027-07-20
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Editorial review complete — This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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